The present disclosure relates to a secondary battery, and in particular to a secondary battery including a current interrupt mechanism.
In some cases, a lithium-ion secondary battery is equipped with a current interrupt mechanism (or a CID (Current Interrupt Device) mechanism) that interrupts (i.e., cuts off) a current when an internal pressure of the battery reaches or exceeds a predetermined value as a safety measure against overcharging. When the lithium-ion secondary battery is overcharged, its electrolyte is decomposed and a gas is generated. The current interrupt mechanism detects a rise in the internal pressure caused by the generated gas when the overcharging occurs, and stops the charging to the lithium-ion secondary battery.
Japanese Unexamined Patent Application Publication No. 2016-95930 discloses a technique related to such a lithium-ion secondary battery equipped with a current interrupt mechanism. In the lithium-ion secondary battery disclosed in Japanese Unexamined Patent Application Publication No. 2016-95930, the current interrupt mechanism is formed by using a reverse plate that is displaced (or deformed) according to a pressure inside a battery case. Specifically, when the internal pressure of the battery case rises and exceeds an operating pressure, the central part of the reverse plate is pressed upward and deformed so that it is raised upward. As a result, a connection point between the reverse plate and a collector terminal is electrically disconnected and hence a conduction path in the current interrupt mechanism is severed. Consequently, a charge/discharge current flowing through the current interrupt mechanism is cut off.